Pagine

What is stereo?

There are now two system of high fidelity, monophonic (monaural) and stereophonic. Monophonic is a system that starts from one microphone and is fed through a single high fidelity set. Stereophonic is a double system. Two separate microphones are placed at different sides of the orchestra and two different systems are used to keep the two signals or channels separated. Two separate speakers are used, placed on different sides of you room. Stereo is much like 3-D photography, two slightly different sound reach your ears giving you a new dimension in sound.

The HR-X features a triple laminated chassis (Acrylic-Aluminum-Acrylic), integral air suspension (which rejects up to 98% of acoustic feedback) and an inverted main bearing incorporating a hardened steel ball running on a Teflon/Delrin composite.

An outer periphery record clamp centers on the platter, not the record, to provide vacuum-like

hold down without the problems inherent in a vacuum system. The drive system uses two lowpowered 24-pole motors driving a 12-pound flywheel, the flywheel spins at 300 RPM and has 62 times the inertia of a 25 pound platter. The drive system and the periphery clamp result in wow, flutter, and rumble that are all below measurabilityproviding the most stablesound ever heard from a turntable.

The VPI HR-X's triple layered X-shaped plinth has a gorgeous, glossy black finish with aluminum accents, an air bearing suspension, an ingenious motor & flywheel combo and equipped with VPI's best tonearm, the JMW-12.7. The best part is, the HR-X only takes up 25” x 19” of space. Every aspect of the VPI HR-X has been optimized for maximum performance. The acrylic platter is cut to tolerances within five thousandths of an inch and sits on an inverted bearing for lower noise and lower rotational inertia. The JMW 12.7 tonearm is mounted directly to the HR-X plinth for exceptional rigidity. The new HR-X drive system consists of two ultra-low powered motors on either side of a seven pound, center mounted flywheel which spins at 500 RPM. The included Outer Ring Clamp works like a vacuum to hold down the outside edge of the record. The SDS speed controller delivers absolute speed accuracy.

The new JMW 12.5i Memorial tonearm begins where the JMW 12 left off. Although they share much of their predecessors' design, including the precision unipivot, damped stainless steel/aluminum arm tube, the 12.5i incorporates several significant improvements.

A secondary mounting with underbase has been placed between the arm rest and the arm lift to greatly improve the arm's rigidity literally making these the only arms that can do VTA adjustments while listening and then be locked as rigid as a solid mounted arm. Do not discount this function, it counts for the speed and low bass detail in the 12.5i.

Nordost Valhalla wire is standard.

The Synchronous Drive System (SDS) combines a turntable motor speedcontroller and a line isolator into one convenient 16” x 3” x 12” (W x H x D) package. The SDS breaks new ground in clean accurate power delivery using advanced digital technology and quartz crystal accuracy. The SDS allows for the adjustment of both the voltage and frequency fed to the turntable motor. Adjustments are easily made from the front panel using intuitive, soft touch controls. The selected output voltage and frequency are shown using large, easy to read LE D displays.

The SDS slowly ramps the voltage and frequency up or down to the selected value in order to prevent premature motor wear due to abrupt changes. During motor startup, the SDS increases its output voltage in order to bring the platter up to speed quickly. Once the desired platter speed has been reached, the SDS ramps the output voltage down in order to reduce motor vibration and, therefore, the systems noise floor. The circuit used in the SDS provides an incredibly accurate line frequency of great stability. Additionally, the electronic circuitry effectively isolates the output voltage from the input voltage, doing away with voltage spikes,

low level fluctuations, RF I, and frequency variations. Instead of merely filtering the power line, the SDS first changes it into pure DC voltage and then digitally regenerates its own clean signal. This approach is superior to that used in many of the other power lineconditioners on the market. The SDS works best with synchronous motor driven tumtables, such asthose from VPI. The speed of a synchronous motor is determined by thefrequency it is fed. It is only logical then, that a device whose speed is based on the line frequency will always function better when a stable frequency is delivered. A constant motor speed translates into a quieter, more faithful musical presentation.

The philosophy of GM 7O phono stage design, is the most typical for GRAAF, followed for its whole production. It regards mainly the insertion of the active elements in an environment that is able to let them express their complete potential. The same importance is given to the full exploitation of each component own characteristics, so to avoid the use of additional circuits, which could interfere on the musicality of the performance. Therefore, RF filtering is obtained by the inner characteristics of active components used, and not with the recourse to a passive network. In the same way, in order to obtain the correct input sensitivity for MC cartridges, there is not any additional gain stage. Instead, a variable gain Implement has been chosen, because it has a simpler lay out and is more transparent to music.

RIAA eq is made by a completely passive network, placed after the gain stage. Its components have been calibrated with the greatest care to maximize the response precision and the purity of the musical signal, with the help of critical listening tests as well. Power supply implements the same transformers section of GM 13.5 B II, quite huge, followed by independent filtering for gain and RIAA stage, and for output stage.

The correct electric interface between cartridge and phono stage has been carefully regarded. The knob on the back side of the unit is for the selection of six different impedance loads. Wishing to have a custom load, it is possible to use the upper RCA plugs to connect a resistance of the proper value.

The input stage is based on two pairs of PC 9OO tubes. Gain stage and output buffer stage use a pair of 6922 tubes each, chosen for their linearity, low noise and musical characteristics. The active components used by GM 7O and the whole GRAAF production are subject to a very hard selection, that guarantee the full correspondence of each unit to the reference specifications.

Built manually one by one, with components selected with the greatest care, tested by a severe burn in procedure that go on no stop for several days, each one presented to the definitive approval of the designer in person, given only after a careful listening test, GRAAF electronics have all the qualities to fulfil the most discerning of the listeners, first of all for purity of sound and luminousness of timbre.

The GM 2O power amplifier uses an OTL (output transformerless) and OCL (output capacitorless) configurafion. The benefits of this type of circuit are very widely recognised and may be summarised as providing unrivalled transparency, speed and dynamics. OTL / OCL designs avoid the need to couple the loudspeaker load by means of an output transformer. In the GM 2O therefore the output stages are directly coupled to their respective loads. The circuit in each of the two power stages is based on a bridge in which the 6C33C tubes represent two of the four sides. The GM 2O uses a fully differential and balanced configuration (i.e. symmetrical) and is DC coupled between each of its stages with great benefits in terms of immunity to noise, including noise from AC mains.

Great care has been taken to ensure stability in all the working stages of the amplifier, making them practically immune to variations in the characteristics of the active components (thermic, static and dynamic) and maintaining their special character unaltered over time. The power supply is made up of six distinct sections, four of which float with respect to ground and provide power for the output stages. The remaining two sections provide power for the driver and gain stages. This method of supplying energy to the various stages of the amplifier is an excellent solution to the problems inherent in providing many different voltage values which are commonly used in valve amplifiers.

Two 6C33C triode valves are used in each of the two channels' power stages, conceived in such a way as to make the best use of the ability of these tubes to give high current with a low voltage power supply. These power tubes, not normally used in less sophisticated circuits, represent an ideal choice for an OTL design thanks to their great robustness and surprisingly good sound quality.

The power amplifier input stage uses two 6922 double triodes which are not only responsible for the voltage gain but also operate as impedance adaptors. The driver stages, working with two triode-coupled

EF 1 84 pentodes, take advantage of the differential circuit mentioned above and work also as phase splitters. This guarantees good driving ability for the power tube grids and perfect symmetry between the two signals, which are in push-pull mode, and are used from the power stages.

It's important to add that each channel voltage gain and driver create together a double differential cascade stage which is able to create a high CMRR.

The stabilizing offset and bias circuits fitted to this power amplifer ensure completely trouble-free setting-up. In the GM 2O loudspeaker protection is guaranteed by a sophisticated circuit which does not make use of series relays or current limiters, since the tubes themselves are naturally current-limiting.

A small amount of feedback (6dB) is used to allow the GM 20 to drive even difficult loudspeaker loads without problems.

The particular circuit design described above allow excellent results to be obtained from the GM 2O.

As can be seen from the attached specifications, the performance is of a very high order. For example, the bandwidth extends from 1 Hz to beyond 35OKhz!

As befits an amplifier of this class, it is possible to use the two inputs L and R in balanced mode by means of XLR plugs or in unbalanced mode via RCA phono plugs.

This is our
lowest-priced turntable, yet we confidently invite you to compare it with
anyone else's highest-priced turntable. Your're not likely to find a tonearm
that seriously matches the CS1237's with its four-point gyroscopic gimbal
suspension and all th eother design features with other Dual tonearms.

You might,
in fact compare the CS1237 tonearm with one of the more exotic separates.
You'll find they cost as much as the entire CS1237

Among the
CS1237's many features are the folowing:

The cueing
system is damped in both directions to prevent bounce.

Pitch control is variable over a 6 percent range.

The strobe
platter is die-cast aluminum and machine-balanced.

Vertical-bearing
friction is astonishingly low-less than 8 milligrams. it can track as low as
0,25 gram - which means it will allow any cartridge to operate at its own
optimum tracking force.

And if you
compare the CS1237 with the higher-priced Dual turntables you'll find they have
additional refinements, but no difference in design integrity or manufacturing
quality.

The CS
1237's tonearm is mounted in a four-point gyroscopic gimbal-widely acknowledged
as the finest suspension system available. The tonearm is centred, balanced and
pivoted exactly where the vertical and horizontal axes intersect.

From pivot
to tonearm head, the shape is a straight line, the shortest distance between
those two important points. Curved tonearms may look sexier, but at the cost of
extra mass, less rigidity and lateral imbalance - none of which is consistent
with good engineering practice.

Tracking
force is applied by a flat-wound spring coiled around the vertical pivot, and
this force is maintained equally on each groov wall whether or not the
turntable is level. The tonearms's perfect balance is maintained throughout
play.

By contrast,
tonearms which apply tracking force by shifting the counterweight forward are
actually unbalanced during play and prone to mistracking. For example, on
warped records the stylus tends to dig in on the uphill side of the warp and to
lose contact on the way down.

Vertical-bearing
friction in the CS 1237 tonearm is astonishingly low - less than 8 milligrams.
It can track as low as 0,25 gram - which means it will allow any cartridge to
operate at its own optimum tracking force.

There's still more. The counterweight is carefully
damped to attenuate tonearm resonances. Anti-skating is separately calibrated
for all stylus types. Cueing is damped in both directions to prevent bounce.
And because the CS 1237 can play up to six records in sequence, the stylus
angle can be set for optimum vertical tracking in either single-play or
multiple-play.

To find any
other tonearm that seriously matches the CS 1237's, you have two choice.

You can
consider one of the more exotic separates. But you'll find they cost as much as
the entire CS 1237 (price: less than $180, complete with base and cover)

Or you might
compare it with one ofthe higher-priced Dual turntables. You'll find a few
additional refinements, but no difference in design integrity or manufacturing
quality. Which is why no other turntable quite matches a Dual , any Dual

all Dual
tonearms are mounted in this four-point gyroscopic gimbal. Tonearm mass
iscentered and pivots precisely where the vertical and horizontal axec
intersect

Sansui has
again challenged traditional thinking in speaker system design. And again the
results mean spectacular improvements in reproduced sound under actual
listening conditions in your home. The new LM Series represents not just a
revolution in design but a re-evaluation of high fidelity reproduction
standards as well. Another great step in the realistic world of musical sound.

The unique
multi-radiation baffle for the LM (Linear Motion) tweeter driver utilizes back
radiated sound energy to enhance the overall sense of perspective sound image
resolution and location in actual stereo application. It features three
exponential horns to channel some of the out-of-phase backradiated sounds of
the tweeter into the listening field. Essentially this unusual design
emphasizes certain phase difference relationships in multi-channel music to
give us a greater sense of stereo perspective. The fact that the
separately-baffled LM tweeter driver has very free movement against input
signals means better transient response too much better.

The LM
Tweeter itself is a Sansui-exclusive Linear Motion Driver with a CCAW
(Copper-Clad Aluminum Wire) voice coil to reduce moving mass and help improve
transient response. The diaphragm features a steeply convex phase equalizer to
eliminate phase interference inside the cone for better high-end response.

Improved
Transient Response

Since the LM
Tweeter is mounted on a separate baffle, as explained below, it requires no
back cap or cavity to block out the strong and potentially damaging high
pressure waves created by the woofer in the enclosure. The die-cast aluminium
frame on the tweeter itself is ported to correspond to the three openings in
the multi-radiation baffle, and the tweeter diaphragm is free to move to and
fro in linear response to input signals with fast rise time. The result is free
Linear Motion in the air on in technical terms, better transient response. The
pure sounds of the LM Tweeter prove the
advantages over the blurred and muddy effects of less transient types at
first hearing.

MULTI
RADIATION BAFFLE

Three
Horn-Shaped Ports

The special
baffle for the LM Tweeter is mounted independently on the upper front of the LM
enclosure. As illustrated its three ports in the tweeter assembly to channel
the back-radiated sounds of the tweeter into the listening area in three
directions - left, right and up. After testing over thirty full-scale LM
prototypes, and the baffle as it appears here has been proven to emit just
enough sound information in the high frequency range to achieve the unusually
effective results .

Greater
Stereo perspective

The sense of
presence and ambience in stereo sound is much improved by the unique LM
approach of course. But it is in the precise sound-image location effect that
the new design truly shows its stuff. The emphasis on the difference in sound
pressure levels inn the respective channels means that any and all between the
channels sound images can be located exactly as they were intended by the
recording engineer.

Enlarging
each image as some speaker systems claim to do is not the answer to better
stereo perspective. The LM approach in fact makes each individual image smaller
with no loss in perceived level. In this way each has a more distinct focus or
identity, more breathing room, more personality. And when they are located
along the sterohorizot the perspective itself seems to widen and deepen as it
does in live listening conditions.

Natural
Response Woofer

The
low-frequency driver in the LM has a number of unusually advanced features for
mor natural bass respons, making it the perfect mate for the improved LM
Tweeter system.

The
superlight woofer cone is formed by a special non-press molding process and
features a unique multi-corrugation design to achieve for proper stiffness and
internal loss to create a living bass tone. To suspend this cone without
defeating its best qualities. Sansui engineers designed an accordion-crease
surround itself of appropriate stiffness and acoustical properties. The concave
equalizer in the throat of the cone is still another new Sansui design and it
serves perfectly to improve response near the crossover frequency. Finally, the
LM woofer features a particularly strong magnetic circuit and voice coil,
further extending the unit's ability to respond with linear motion to even
extremely high level input signals with proper damping for improved linearity.

Special
Crossover network

The
crossover network in each LM model uses a special high-permeability core
inductor to reduce DC resistance. This in turn provides a high damping factor
and holds distortion to 1,0% or below even when maximum (peak) power is
introduced. The non-polarized electrolytic type capacitors of particularly
lower energy loss in the high (above 10,000 Hz) frequency are 1,500 Hz and high frequency response can be adjusted
by a rear panel control.

Luxurious
Cabinet

Every LM
Series speaker system regardless of size or power- handling capacity is crafted
to blend harmoniously with all room decors. The polished walnut grained wood
cabinet is solidly built and expertly finished with pride and the trim,
pleasingly-textured front grille is a one-piece, removeable unit which protects
both the separately-mounted LM Tweeter and the woofer cone.

Ever since the advent of pulse coding method to record electric signals, the world of reproduced music is about to underego significant changes, because the digital recording technology has brought about substantial improvement in the reality of the reproduced music. Moreover, minute and subtle reverbration components, which are essential to reproduce the atmosphere of the original sounds, can now be recorded with utmost accuracy.

Needless to say, accurate transmission of signals is indispensable in the reproduced sound fields; otherwise, we cannot even appreciate the reproduced music and in the worst case, we may not be able to perceive what we listen to as music but nothing more than collection of noises. Equally important for reproducing music, however is an amplifier that can correctly amplify even reverbration components to reproduced music, as if the music were being played by an orchestra right in front of you. Without such an amplifier, the atmosphere of beautiful and elegant music cannot be reproduced. It is therefore vital for a power amplifier to be able to yield power of high amplitude and, at the same time, to amplify minute signals superimposed on the electric signals it amplifies, with high fidelity. However the power an amplifier can produce and its fidelity are, in many case, in a mutual contradictory relation, and the higher power an amplifier can produce, the lower its fidelity in reproducing minute signals and reverberation components. The P-800 which was developed with Accuphase's technology that has already produced a superb monophonic amplifier, M-1000 is an exceptional power amplifier in this respect as it can yield a power of as high as 600 watts (into 4 ohm loads), but reproduce even reverberation components with high fidelity, which is not possible with most of the amplifiers on the market today. Its uses two power units in bridged configuration, forming a totally balanced amplifier, meticulous attention has been paid to every detail, and original Accuphase technology is used throughout, with the aim to improve quality especially at low signal levels.

The impedance of loudspeakers on the market varies considerably, ranging from about 2 ohms to 16 ohms. With a direct-coupled amplifier, driving such a wide impedance range with equal aplomb is almost impossible. An output stage designed for optimum performance at 2 ohms will deliver less power into 8 to 16 ohms. Conversely, the performance of an amplifier optimiozed for about 4 to 8 ohms suffers at 2 ohms and it will not be capable of driving 1-ohms loads.The P-800 incorporates a special design to deal with a wide range of load impedances. The applied voltage of its output devices can be switched to a lower value, to provide the high current capability required by low-impedance loads. This results in a truly amazing guaranteed rating of 600 watts into 1 ohm and 400 watts into 2 ohms, with undiminshed sound quality. To achieve such stunning performance the output stage of each power unit employs two sets of seven parallel push-pull pairs of wide-band transistors with a maximum power dissipation of 130 watts each. This amounts to 14 pairs or 28 transistors per unit, totaling a maximum powe dissipation of 3,6 kilowatts. These truly astounding figures testify to the no-holds-barred Design approach of the P-800.To let you monitor its performance, the P-800 incorporates two symmetrically arranged analog level meters.The beautiful and simple elegance of this amplifier's external appearance belles its awesome performance. But when turned on, it speaks unmistakably through music.

Compact Disc Player8-times oversampling digital filter: Higher resolution and lower noiseThe CD format uses a sampling frequency of 44,1 kHz, to provide a frequency bandwidth of from about 0 Hz to 20 kHz. This frequency can result in the generation of "sampling" noise because its "foldover" frequencies are spactrally close to he audible frequency range. These spurious frequencies - known as sampling noise - are normally eliminated by a higher-order analog filter with steep attenuation response. Such filters, though tend to cause aphase lag in frequencies of 10 kHz and highr, making accurate signal reproduction impossible.Our 8-times oversampling digital filter offers the solution. It samples the input signal at 8 times the normal frequency (that's 352,8 kHz), shifting the spurious frequenciec far out of the audio range. This makes it possible for us to use a low-order analog filter , made from high-quality discrete parts,with mild attenuation response to remove the spurious frequencies. So our 8-times over-sampling digital filter ends due to folder frequencies, whike maintaining accurate phase linearity up to 20 kHz and enabling low distortion output.Accu-Focus System: For better frequency response in RF outputThe laser beam teht reflects off pits on the surface of tehCD holds billions of bits of digital musical information. The beam is detected by a pickup and the signals are passed on to a photodetector where they are converted into electric RF signals. The photodetector is divided into four components to control the focus servo, inevitably causing phase difference between the four signals the detector has received. The accu-Focus System, however, solves this phase-related problem by adding a delay circuit for the first - ariving signals thus dramatically reducing distortionand improving frequency response in the RF out[ut, especially at high frequencies. As a result, boot noise and distortion, are reduced in the audible frequency range.

Linear-envelope D/A conventer system with twin glitch-less ConvertersOur linear-envelope D/A converter system is one of the most advanced designs. Conventional converents use 16 current sources to convert 16-bit data into analog; with them even the slightest error in the current sourcs can lead to conversion distortion. With our new linear-envelope converter, however, we've virtuality eliminated the current-source error. Thus ending conversion distortion.Moreover there are two converters, one for each channelto end inter-channel phase difference and to provide better sound imaging. And each is a glitch-free type for lower noise.

Class-A FET buffer amp: For reduced distortion and improved sound qualityFour separate power supplies: Clean sound beacause analog circuits are insulated from digital crcuitsAnti-resonance concept: Honeycomb chassis, magnetic-clamp disc stabilizer, large insulatorsTo ensure superb disc tracking and great sound, we,ve come up with the Anti-resonance concept. This concept is expressed in our CD players in the following ways.The chassis of all our CD players have a ribbed honeycomb construction. This design not only increasses rigidity but also protects the pickup and disc drive system inside from vibration generated by speakers and other external influences.

The
330D was the ultimate development of Scott's stereo AM/FM tuner line, designed
to receive stereo AM/FM simulcasts. The switching provisions were much improved
over those of the 330C, to provide more flexibility for the reception of AM/FM
simulcasts. The slide switch was changed back to the configuration it had on
the 330B, to allow switching the tuning meter between the AM and FM tuner
sections, without disturbing reception. The power switch was converted to serve
as the mono/stereo switch, in addition to switching power. In addition to
positions for power off, monophonic operation, and stereophonic operation, it
had a fourth position for stereo phase reverse. The phase revere position was
useful in receiving stereo AM/FM simulcasts, to correct for reversed phase at
one of the transmitters. In the 330D, a 6CN7 was used as the AM detector,
replacing the 6AL5 in the 330C. The 6CN7 provided the extra triode section
needed to implement the stereo phase reverse function.

Solid State Stereo Amplifier180 watts of IHF standard total music power, enough to drive even low efficiency hi-fi speakers.The wide power bandwidth of 10 Hz to 50,000 Hz with very low IM distortion.Kenwood's exclusive low level phono inputs for low level output phono cartridges of 2 mV, 0,5 mV or 0,05 mV.2 pairs of MAG input terminals for 2 set of record players.Lever type -20 dB muting switch of quick response for momentary quietness during telephone call etc.2 dB step type tone controls with tone mode switch. Blue light indicators for input selector switch.Lever type high and low filter switches.Large volume/balance control knob located in center of frontpanel.Pre-amplifier outputs for use with other power amplifier or multichannel system.Main amplifier inputs for the use with other pre-amplifier, tuner and tape recorder with pre-amplifier, and also these unputs enable you to drive the main amplifier directly.Speaker terminals for 2 sets of stereo speaker and front panel speaker selector switch.Exclusive blow-out proof automatic circuit breaker protects power transistors.

The CDA823 is an evolution of the renowned CDA822 CD-player. While employing the same outstanding DACs and analog amplifiers as its predecessor, double resampling and reading speed are now introduced. Increased over-sampling of 192 kHz is used to avoid the loss of energy and transparency in a complex analog output filter. The CDA823 also allows for future updates of firmware through flash programmable microprocessors.The CDA823 uses a true 24-bit, high-resolution, dual differential, digital to analog converter with current output for widest dynamic ranges, fast conversion and lowest noise. Jitter distortion arising from time errors is virtually eliminated by sample rate converters and our precision internal master-clock. All audio power supplies are multi-regulated. The output amplifiers are a priority in the design of this audiophile CD-player. Operational amplifiers with their fixed working conditions and sound qualities can become an obstacle when the designer wants to be in control of the final performance. Therefore, CDA823 employs discrete class-A input amplifiers with carefully selected operational points for the specific electronic environment in which they have to perform. The output circuitry provides both fully balanced and single ended outputs.